458 BRITISH LEPIDOPTERA. 



evidently quite independent in origin, and for purposes that are quite 

 clear, viz., the strengthening of the wing in this region in the Psychids, 

 because of the mode of copulation and chance of injury to the wing 

 (vide, ante., pp. 275, 368, 373, 377), and in certain Lachneids (usually 

 of the most specialised type), to carry the extension of the wing- 

 membrane in the costal region of the base of the hindwings, which 

 is developed in order to complete the similarity of the imagines possess- 

 ing this enlargement, to a leaf, which they resemble when at rest. 

 These and our own remarks on the subject (ante., vol. i., pp. Ill, 128- 

 121, and Proc. South Land. Ent. Soc, 1898, pp. 1-11) and Dyar's friendly 

 criticism thereof (Ent. Record, xi., pp. 141-2) comprise, so far as we 

 are aware, all that has been written on the subject. 



The question that interests us here, however, is the relationship of the 

 Lachneid genera, &c, inter se, and anything we may say must be taken 

 largely as an expression of ignorance, so little do we know of the structure 

 of the early stages of any but our British and one or two common Euro- 

 pean species. Our species are representatives of isolated and separate 

 genera, mostly belonging structurally to widely differing tribes, and an 

 attempt to show their relationship is, as Bacot suggests, an attempt 

 to "obtain the configuration of a submerged continent, with only a 

 few mountain peaks that one can examine above the surface, together 

 with a few soundings, and a glance at the colour of the water." In an 

 earlier paper (Proc. South Pond. Ent. Soc, 1898, pp. 1-11) we suggested 

 that our British species fell into at least six tribes, and we see no 

 reason for altering our opinion, except that we now suspect that 

 Macrothylacia is rather more separate from Malacosoma than we 

 asserted, and that we should give equal if not greater weight to the 

 Eutrichid side of our tree, separate Pachygastria from Pasiocampa 

 generically (this is evident from a study of the newly-hatched larva), 

 and give Malacosoma and Pachneis (Eriogaster) a much lower position as 

 generalised forms. These we can discuss in more detail later. 

 Meyrick dismisses the phylogeny of the Lachneids thus : " Odonestis 

 (Cosmotriche) and Gastropacha (Eutricha) are correlated early types ; 

 Clisiocampa (Malacosoma) and Eriogaster (Pachneis, Poecilocampa, 

 Trichiura and Macrothylacia) are developments of Odonestis (Cosmotriche) 

 and Pasiocampa of Eriogaster (Pachneis, &c.)." We may agree at once 

 that Cosmotriche and Eutricha are correlated types, since both are well- 

 defined Eutrichid genera, but how can Malacosoma and Eriogaster, 

 Meyr. (which includes Poecilocampa, Trichiura, Macrothylacia and 

 Pachneis) be developments of Cosmotriche .' Can the eggs of the former 

 genera be derived from the latter ? Can the generalised tubercular 

 warts of the first larval stadium of Malacosoma be derived from the 

 large specialised warts of the latter ? Is the pupa of Cosmotriche more 

 generalised than the pupa? of Erioy aster, Meyr., which comprises the 

 species of four of our Lachneid genera ? Even in neuration, can we 

 derive the comparatively simple, supplementary, basal cell of the 

 hindwings of Poecilocampa, Trichiura, Eriogaster and Macrothylacia 

 from the more specialised one of Cosmotriche, which Dyar, we think 

 erroneously, places even higher than Epicnaptera ! We suspect that 

 Pasiocampa is derivable from Meyrick'' s Eriogaster, inasmuch as the latter 

 includes the more generalised branches of the stem of which Pasiocampa 

 is the most specialised branch, but the phylogeny that places Poecilo- 

 campa populi, Trichiura crataegi, Pachneis lanestris and Macrothylacia 



